The two backbone processes of rubber manufacturing answer different questions: compression molding answers what shape; extrusion answers how long.
Compression molding: a preform of rubber is placed in a heated mold, pressed, and vulcanized into a discrete part. Capabilities: full 3D geometry, inserts and overmolding, tight tolerances (±0.1mm typical, ±0.05mm achievable on small parts), multi-cavity economics. Limits: one cavity set per part number; cure time dominates the cycle. Typical products: molded O-rings, grommets, mounts, bellows, custom cases.
Extrusion: compound is forced through a die and continuously vulcanized. Capabilities: constant cross-section at any length, near-zero per-length tooling, excellent economics for tubing and profiles. Limits: constant cross-section only; dimensional tolerance looser (±0.2mm typical); secondary operations (cutting, splicing, vulcanized joining) needed for finished parts. Typical products: tubing, cord, seals and strips, profiles — including O-ring cord spliced into rings.
How they cooperate: large O-rings beyond mold capacity are extruded as cord and splice-bonded seamless; gasket frames combine extruded profiles with vulcanized corners; a single machine enclosure may carry molded grommets, an extruded door strip and a molded case.
Selection shortcut: 3D shape or inserts means compression; constant cross-section means extrusion; both means hybrid, quoted as one BOM.